This invention relates to thermal hot-melt adhesive bonding of elements of dissimilar materials, and particularly bonding of a fabric lined member to a plastic member.
Plastic members are conveniently bonded to each other with a fusion bond between the plastic members. The plastic members are mounted in appropriate superimposed relation. Heat and pressure are then applied over a bond line or area to simultaneously convert the plastic members to a molten or semi-liquid state which, upon cooling, forms a highly effective reliable fusion bond. The junction may be stronger than either of the substrates. Various systems have been used for heating the plastic members. A particularly satisfactory method has been developed and is disclosed in various patents of the present inventors and patents assigned to the assignee of the present invention. For example, U.S. Pat. No. 3,461,014 which issued Aug. 12, 1969 to Wm. C. Heller, Jr. et al and discloses a fusion bonding process based on the unique development. The method generally includes the introduction of gamma ferric oxide particles into the plastic substrate or in a compatible plastic bonding agent interposed between the plastic members at the fusion bond area. A high frequency magnetic field is applied through the bond area, with pressure applied. The high frequency field creates heat in the particles through hysteresic phenomena, with a rapid heating of the plastic members producing a fusion bond. With plastic-to-plastic surfaces, an effective hermetic fusion bond between the members is readily created. Other developers have suggested using larger metal particles in which eddy currents are created in the presence of an appropriate magnetic field to heat the plastic. Other systems merely provide heated bar members which are applied directly to the bond area to effect the fusion bonding.
In certain applications, a fabric lined rubber-like member is to be bonded with a fluid tight connection to another plastic member. A typical application includes bonding of an impervious glove or other similar hand covering to a sleeve member to provide a continuous protective covering over the hand and arm of a user. Suits employing such a continuous hand and arm structure are used in various hazardous environmental conditions. A reliable hermetic connection is therefore essential to maintain the protective enclosure from the surrounding environment. In addition, the glove portion is preferably provided with a fabric lining to provide a more comfortable glove.
Typically, the fabric lined member includes an outer shell of an impervious material such as a rubberized material, latex, plastisol or the like having a fabric lining such as a flocking material. The glove is connected to a plastic sleeve typically of a polyethylene film or similar flexible, impervious plastic. The typical glove with the flocking material and the sleeve material are vastly different materials which are difficult to bond by use of fusion bonding. Further, the melting of the adherend's base materials may require special processing to insure that the continuity of the connection is maintained.
Many other applications exist in which a glove and extended sleeve may advantageously be used such as in handling caustic materials and the like where protection not only of the hands but the arm of the user is essential or desirable.
An alternative to fusion bonding of elements including plastic elements, involves use of a separate adhesive which is applied in liquid or paste form, and forms a joining layer between the elements. Certain hot melt adhesives are available which can be deposited in melted form between the surfaces to be bonded.
Generally, such separate adhesives have not been used for fluid tight connection, because of the superior connection provided by fused materials. The difficulty associated with all bonding is further increased in the bonding of fabric lined material, such as a lined protective plastic glove, and simple application of a hot-melt adhesive has not produced a hermetic connection or a desirable high strength junction.
There is a need however for a simple and effective method of bonding elements of vastly different materials without melting of the elements and particularly a fabric lined rubber-like member, such as a glove or the like, to a plastic surface such as a garment sleeve.